Reducing the mercaptan content of petroleum distillates by treating it with an organic nitrite and a peroxide



REDUCING THE MERCAPTAN CONTENT OF PETRDLEUM DISTILLATES BY TREATING IT WITH AN ORGANIC NITRITE AND A PERCXIDE Peter Urban, Jr., Chicago, Ill., assignor to Universal Oil Products Company, Des Plaines, 111., a corporation of Delaware No Drawing. Application August 11, 1954, Serial No. 449,250

8 Claims. (Cl. 19629) This invention relates to the treatment of petroleum distillates and more particularly to a novel method for reducing the mercaptan content of sour petroleum distillates.

The novel method of the present invention is particularly applicable to the treatment of motor fuels and still more particularly unsaturated gasolines including cracked gasoline, coker distillates, vis. breaker distillates, etc., as well as of saturated gasolines including straight run gasoline, natural gasoline, etc., or a mixture of unsaturated and saturated gasolines. The present invention also may be utilized for the treatment ofother sour petroleum distillates including kerosene, burner oil, diesel oil, gas oil, lubricating oil, fuel oil, etc.

In accordance with the present invention, an alkyl nitrite or a mixture of an alkyl nitrite and a peroxide are added to the petroleum distillate in order to reduce the mercaptan content thereof. In another embodiment, a major proportion of the mercaptan content of the sour petroleum distillate may be reduced by conventional treating with an alkali metal hydroxide solution and particularly sodium hydroxide solution, potassium hydroxide solution or these reagents containing a solubilizer or solutizer including, for example, an alcohol such as methanol, ethanol, etc., phenols, cresols, etc., tannin, isobutyrate, etc. It is understood that any suitable method may be utilized to convert or remove a major proportion of the mercaptans. However, the petroleum distillate usually will not be sweet and will still contain mercaptans. The final sweetening of the petroleum distillate may be effected in accordance with the novel process of the present invention.

In one embodiment, the present invention relates to a process for reducing the mercaptan content of a sour petroleum distillate which comprises treating said distillate with an alkyl nitrite.

In a specific embodiment the present invention relates to a method of treating sour gasoline which comprises incorporating amyl nitrite therein.

In still another embodiment the present invention relates to a process for reducing mercaptan content of sour gasoline which comprises incorporating therein amyl nitrite and t-butyl hydroperoxide.

Any suitable alkyl nitrite may be utilized in accordance with the present invention. Amyl nitrite is particularly preferred. Other nitrites include ethyl nitrite, propyl nitrite, butyl nitrite, hexyl nitrite, heptyl nitrite, octyl nitrite, nonyl nitrite, deeyl nitrite, undecyl nitrite, dodecyl nitrite, etc. or mixtures of two or more alkyl nitrites. The alkyl nitrite may be straight or branched chain and it may be a primary, secondary, or tertiary nitrite. The only requirement of the nitrite is that it is soluble in the petroleum distillate and also that it will react with the mercaptans under the treating conditions.

The alkyl nitrite may be incorporated in the petroleum distillate in any suitable manner. In one method nited States Patent Patented Apr. 30, 1957 the alkyl nitrite is commingled with the sour petroleum distillate and the mixture is passed through suitable mixing devices, including orifice mixers, durion mixers, etc., after which the mixture is passed to a storage tank. In another method, the sour petroleum distillate is passed through a storage or mixing tank and the alkyl nitrite added thereto, preferably followed by some means of intimate mixing as, for example, mixing paddles disposed in the tank or circulation of the liquid from the bottom of the tank through a pump. and back into the top of the tank, etc.

Generally, the treatment of the sour petroleum distillate is eflected at ambient temperature. In some cases, the reaction may be accelerated by efiecting the treatment at an elevated temperature which may range from 100 F. to 400 F. or more depending upon the pressure utilized therein, but usually below that at which substantial vaporization occurs.

In another embodiment, treatment of a sour petroleurn distillate is efiected with both an alkyl nitrite and a peroxide. While hydrogen peroxide may be utilized, it generally is preferred to employ an alkyl peroxide in cluding t-butyl hydroperoxide, cumene hydroperoxide, methylcyclohexyl peroxide, peracetic acid, persuccinic acid, dimethyl peroxide, diethyl peroxide, dipropyl peroxide, dibutyl peroxide, diamyl peroxide, dihexyl peroxide, acetyl benzoyl peroxide, acetyl propionyl peroxide, butyryl peroxide, lauroyl peroxide, benzoyl peroxide, tetralin peroxide, t-butyl perbenzoate, etc., or mixtures thereof. The alkyl nitrite and hydroperoxide may be commingled and then added to the sour petroleum distillate or each compound may be added separately to the sour petroleum distillate. The mixing may be effected in the manner hereinbe'fore set forth.

The amount of alkyl nitrite to be employed should be at least one equivalent of alkyl nitrite per equivalent of inercaptan in the sour petroleum distillate. Usually an excess of alkyl nitrite is employed in order to insure complete reaction and the excess may range up to 10 or more equivalents of alkyl nitrite per equivalent of mercaptan. When the peroxide is employed, it may be utilized in the same concentration as the alkyl nitrite or in a lesser mount which may range from 5 to molecular proportions of peroxide per molecular proportions of alkyl nitrite. However, when utilizing the mixture of nitrite and peroxide, the total concentration thereof may be less than one equivalent per equivalent of mercaptan but, as hereinbefore set forth, generally an excess is used in order to insure complete reaction and therefore it is preferred to utilize at least one equivalent of the nitrite per equivalent of mercaptan contained on the sour petroleum distillate.

While the alkyl nitrites are preferred for use in accordance with the present invention, it is understood that in some cases other organic nitrites and particularly cyclic nitrites may be employed including, for example, phenyl nitrite, naphthyl nitrite, benzyl nitrite, cyclohexyl nitrite, cyclopentyl nitrite, etc. It is understood that the results obtained with the various nitrites are not necessarily equivalent.

As hereinbefore set forth, treatment of the sour petroleum distillate with the alkyl nitrite or the alkyl nitrite and peroxide may be preceded by a treatment with an alkaline solution and particularly caustic solution. Treatment of the sour distillate with alkaline solution generally is effected at ambient temperature and either in a batch or continuous process. in some cases, temperatures up to F. or more may be employed. This will serve to remove from about 50% to about 95% by Weight of the mercaptans contained in the sour gasoline. Following this treatment, the petroleum distillate Example I The gasoline used in this example was a thermally cracked gasoline having a mercaptan content of 0.033% by weight. Upon the addition of equivalents of amyl nitrite for each equivalent of mercaptan and storage at 68 F. for 24 hours, the mercaptan content of the gasoline was reduced to 0.026% by weight.

Example II Another sample of the gasoline described in Example I was treated with 10 equivalents of amyl nitrite and 1.3

equivalents of t-butyl hydroperoxide for each equivalent of mercaptan. After storage at 68 F. for 24 hours, the mercaptan content of the gasoline was decreased to 0.0125

For comparative purposes, the addition of 1.3 equivalents of t-butyl hydroperoxide per equivalent of mercaptan decreased the mercaptan content to 0.0246% by weight. Thus, it will be noted that the use of both the alkyl nitrite and t-butyl hydroperoxide reduced the mercaptan to about half of that obtained when using the t-hutyl hydroperoxide alone.

Example 111 Sour kerosene may be treated by incorporating therein 3 equivalents of hexyl nitrite per equivalent of mercaptan and maintaining the mixture at a temperature of 350 F. until substantially complete reaction of the nitrite with mercaptans is eifected.

I claim as my invention:

1. A process for reducing the mercaptan content of sour petroleum distillate which comprises treating said distillate with alkyl nitrite and peroxide and reacting said compounds with mercaptans present in the distillate. 2. A process for reducing the mercaptan content of sour petroleum distillate which comprises treating said distillate with amyl nitrite and t-butyl hydroperoxidc and reacting said compounds with mercaptans present in the distillate.

3. A process for reducing the mercaptan content of sour petroleum distillate which comprises treating said distillate with amyl nitrite and cumene hydroperoxide and reacting said compound with mercaptans present in the distillate.

4. A process for reducing the mercaptan content of sour gasoline which comprises treating said gasoline with alkyl nitrite and a peroxide and reacting said compound with mercaptans present in the distillate.

5. A process for reducing the mercaptan content of sour gasoline which comprises treating said gasoline with amyl nitrite and t-butyl hydroperoxide and reacting said compounds with mercaptans present in the distillate.

6. A process for reducing the mercaptan content of: sour gasoline which comprises treating said gasoline with amyl nitrite and cumene hydroperoxide and reacting said compound with mercaptans present in the distillate.

7. A process for reducing the mercaptan content of sour gasoline which comprises treating said gasoline with amyl nitrite and hydrogen peroxide and reacting said compounds with mercaptans present in the distillate.

8. A process for reducing the mercaptan content of sour petroleum distillate which comprises treating said distillate with an alkaline solution to remove from about to about 99%.by weight of mercaptans and thereafter treating the distillate with an alkyl nitrite and a peroxide and reacting said nitrite and peroxide with mercaptans remaining in the distillate.

References Cited in the file of this patent UNITED STATES PATENTS 54,495 Brace et al. May 8, 1866 66,364 Loomis et al. July 2, 1867 1,840,269 Borgstrom Jan. 5, 1932 2,593,761 Johnstone Apr. 22, 1952 2,670,319 Ayers et a1 Feb. 23, 1954 

1. A PROCESS FOR REDUCING THE MERCAPTAN CONTENT OF SOUR PETROLEUM DISTILLATE WHICH COMPRISES TREATING SAID DISTILLATE WITH ALKYL NITRITE AND PEROXIDE AND REACTING SAID COMPOUNDS WITH MERCAPTANS PRESENT IN THE DISTILLATE. 